I can not speak for xdelta gui but I can speak for xdelta- it is my chosen patching method unless I have something better. Go command line if you have to. I am still rocking a v1. something version (it has moved on somewhat since this version but

Assuming however the command line stuff has not changed in this regard your command will look something like
"xdelta delta originalrom.nds hackedrom.nds patchfile.file"

Anyhow IPS rarely works on DS roms for two main reasons- 1 is that it is limited to 16 megs in size* and 2 is that it is a dumb method and any shift in the data will be seen as a change; chances are you used some tool to rebuild the entire rom which means the entire rom has effectively changed.

*technically it is 16 minus the end of file (EOF in ASCII) and some implementations (IPS is not exactly a standard) have a window option so you can patch a 16 meg window at X bytes in but not many patchers implement such an extension (again IPS has no real spec).

Im trying to make a translation patch for an NDS game (open up the ROM and change the text in some way). Not literally as easy as opening + retyping something.

Click to expand...

To translate NDS games you can use Hex Editor, I use CrytalTile2 to translate NDS games. Of course it's not easy to translate games, but if you're a programmer it would be very helpful.
To make a patch I always use xdelta, very easy to use.

Im trying to make a translation patch for an NDS game (open up the ROM and change the text in some way). Not literally as easy as opening + retyping something.

Click to expand...

To translate NDS games you can use Hex Editor, I use CrytalTile2 to translate NDS games. Of course it's not easy to translate games, but if you're a programmer it would be very helpful.
To make a patch I always use xdelta, very easy to use.